The present invention is generally directed to an information retrieval system of the type which automatically retrieves selected information bearing elements for inspection. The present invention is more particularly directed to an automatic film searching and retrieval system for use with film having a plurality of consecutively numbered frames, and wherein each frame includes an information image and an adjacent frame marker.
Information retrieval systems are well known. One efficient type of retrieval system that has found widespread acceptance is often referred to as a microfilm retrieval system. In such systems, copies of documents and/or data are recorded on film such as 16 mm film wherein each film frame comprises an information bearing element. With the size of the film frames being on the order of 1 mm per document inch, such size reduction affords a substantial reduction in information storage volume and greatly simplifies handling of the information. Such a reduction in size necessarily inhibits direct reading of the information bearing elements or film frames and the usual procedure for reading them is to project the film frame images onto a screen and to magnify them to a size corresponding approximately to the original size of the information document that is recorded.
Because literally thousands of information bearing elements or film frames comprise a roll of microfilm, searching for a particular image film frame can be time consuming. As an example, microfilm reels are known to include information bearing elements or frames on the order of 40,000 frames per reel. To provide ready access to a preselected information bearing element or film frame, automatic search techniques have been developed in the form of automatic retrieval systems.
In such systems, the film frames of the microfilm reels are numbered consecutively for identification and each film frame has an adjacent marker which may be sensed so that as the film frames are scanned they may be counted and the identification numbers displayed. Hence, at the end of a scan cycle the display provides the current number of the film frame being inspected.
Retrieval systems also include a means for entering a target number which identifies the film frame to be inspected. Suitable logic within the retrieval systems determines from the current number and the target number whether the film is to be driven in an up direction or a down direction to arrive at the preselected film frame to be inspected.
The logic control of film retrieval systems are of a finite capacity having a capacity for handling film frame identification numbers of only n digits. Consequently, such retrieval systems include displays of n digits, and counters, comparators, or the like having n digit capacities. Thus, for microfilm reels having frames with identification numbers up to 99,999, a five digit retrieval system is appropriate. Unfortunately, however, a reel of microfilm may have as many as 40,000 consecutively numbered film frames, numbered from, for example, 80,000 to 120,000. The prior retrieval systems having a finite capacity of five digits cannot possibly handle such reels.
For example, given a microfilm reel having 40,000 frames numbered 80,000 to 120,000, and assuming it is required to search for a film frame numbered 110,000 from a currently inspected film frame numbered 90,000, when the target number of 110,000 is entered into the control logic and displayed, the target number will be shifted into the display and will appear as 10,000 (on a five digit retrieval system). When the logic then compares the current number of 90,000 to the target number of 10,000, it will determine that the film must be scanned in the downward direction to arrive at the preselected document. However, in actuality, the film must be scanned in the upward direction to go from the current film frame of 90,000 to the target film frame of 110,000.
From the foregoing, it can be seen that prior retrieval systems are only capable of handling information bearing elements which have identification numbers of a fixed predetermined number of digits or less. Where many information elements must be stored, duplication of identification numbers cannot be avoided. Obviously, such duplication can cause information storing problems.
It is, therefore, an object of the present invention to provide a new and improved information retrieval system.
It is a further object of the present invention to provide an information retrieval system having expanded logic control capabilities.
It is a still further object of the present invention to provide an information retrieval system of the type which automatically retrieves selected information bearing elements for inspection, which information bearing elements are numbered consecutively for identification, and wherein the information retrieval system is capable of handling information bearing elements having identification numbers of any number of digits.
It is a still more particular object of the present invention to provide an automatic film searching and retrieval system for use with film having a plurality of consecutively numbered frames and wherein the retrieval system is capable of handling reels of film having film frames with identification numbers of any number of digits.
It is a still further object of the present invention to provide a new and improved method of retrieving and scanning information bearing elements for inspection.